In a stem cell transplant — also called a bone marrow transplant — a patient's blood-forming stem cells are replaced by infusing new ones into his or her bloodstream. The procedure can be an effective form of treatment for certain forms of cancer, specific genetic diseases, and other types of blood disorders. For most people, the aim of the transplant is to cure the disease.

Blood-Forming Stem Cells

Blood-forming, or hematopoietic, stem cells are immature cells that can develop into any type of blood cell, including:

platelets, which are important in blood clotting and controlling bleeding

Stem cells are produced in the bone marrow, a sponge-like tissue that is found inside large bones (for example, in the breastbone, pelvis, ribs, and spine). Before a transplant, stem cells can be collected from a person's bone marrow or from the bloodstream, where peripheral blood stem cells (PBSCs) circulate.

Another source of stem cells is blood from a newborn's umbilical cord and placenta, which can be donated to a stem cell bank by the baby's mother.

Types of Transplantation

The are two main types of transplant: autologous transplant, in which a patient's own stem cells are collected and then transplanted back into the patient, and allogeneic transplant, in which the stem cells are obtained from another person, most commonly a brother or sister.

Before an autologous or allogeneic transplant, a patient receives either chemotherapy or a combination of chemotherapy and radiation. This treatment, called the preparative regimen or conditioning, eradicates cancerous cells as well as the blood-forming stem cells in the bone marrow, decreasing the number of mature blood cells in a person’s body.

Next, stem cells are infused into the patient's bloodstream through an intravenouscatheter, in a procedure that is similar to a blood transfusion. No surgery is required. Over the following days, the transplanted stem cells travel to the bone marrow, where they will grow and develop into new mature blood cells, including red and white blood cells and platelets.

It usually takes several weeks before all the mature blood cells are replenished. During this time, special measures are taken to protect the patient from infections and bleeding.

Successful autologous and allogeneic transplants provide patients with new, healthy bone marrow. Allogeneic transplants also give patients a new immune system, which is derived from the donor's stem cells and may provide protection against cancer.

Diseases Treated with Transplantation

Different types of transplants are known to be more effective for some diseases than others. Your team of doctors will determine which type of transplant is best for you after considering the specifics of your disease and a number of other factors — for instance, what other treatments you have received and your general health status. Your transplant doctor will discuss these factors in detail with you.

Who Is Eligible for a Transplant?

Transplantation can be an extremely challenging procedure for a patient and family. This is both because of the toxicity of the high-dose preparative regimens and the extended period during which the patient’s immune system is suppressed. For this reason, physicians carefully select patients for this procedure. Newer technology has allowed us to transplant patients who are older and sicker, but an extensive pre-transplant evaluation is still necessary.

allogeneic (A-loh-jeh-NAY-ik)

Taken from different individuals of the same species. Also called allogenic.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

autologous (aw-TAH-luh-gus)

Taken from an individual's own tissues, cells, or DNA.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

blood (blud)

A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

blood transfusion (blud tranz-FYOO-zhun)

A procedure in which a person is given an infusion of whole blood or parts of blood. The blood may be donated by another person, or it may have been taken from the patient earlier and stored until needed. Also called transfusion.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

bone marrow (bone MAYR-oh)

The soft, sponge-like tissue in the center of most bones. It produces white blood cells, red blood cells, and platelets.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

breastbone (brest-bone)

The long flat bone that forms the center front of the chest wall. The breastbone is attached to the collarbone and the first seven ribs. Also called sternum.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

cancer (KAN-ser)

A term for diseases in which abnormal cells divide without control and can invade nearby tissues. Cancer cells can also spread to other parts of the body through the blood and lymph systems. There are several main types of cancer. Carcinoma is a cancer that begins in the skin or in tissues that line or cover internal organs. Sarcoma is a cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue. Leukemia is a cancer that starts in blood-forming tissue such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Lymphoma and multiple myeloma are cancers that begin in the cells of the immune system. Central nervous system cancers are cancers that begin in the tissues of the brain and spinal cord. Also called malignancy.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

catheter (KA-theh-ter)

A flexible tube used to deliver fluids into or withdraw fluids from the body.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

cell (sel)

The individual unit that makes up the tissues of the body. All living things are made up of one or more cells.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

chemotherapy (KEE-moh-THAYR-uh-pee)

Treatment with drugs that kill cancer cells.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

cure (kyoor)

To heal or restore health; a treatment to restore health.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

familial

A phenotype or trait that occurs with greater frequency in a given family than in the general population; familial traits may have a genetic and/or nongenetic etiology.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

genetic (jeh-NEH-tik)

Inherited; having to do with information that is passed from parents to offspring through genes in sperm and egg cells.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

immune system (ih-MYOON SIS-tem)

The complex group of organs and cells that defends the body against infections and other diseases.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

intravenous (IN-truh-VEE-nus)

Into or within a vein. Intravenous usually refers to a way of giving a drug or other substance through a needle or tube inserted into a vein. Also called IV.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

oxygen (OK-sih-jen)

A colorless, odorless gas. It is needed for animal and plant life. Oxygen that is breathed in enters the blood from the lungs and travels to the tissues.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

pelvis (PEL-vus)

The lower part of the abdomen, located between the hip bones.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

peripheral blood (peh-RIH-feh-rul blud)

Blood circulating throughout the body.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

placenta (pluh-SEN-tuh)

The organ that nourishes the developing fetus in the uterus.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

radiation (RAY-dee-AY-shun)

Energy released in the form of particle or electromagnetic waves. Common sources of radiation include radon gas, cosmic rays from outer space, medical x-rays, and energy given off by a radioisotope (unstable form of a chemical element that releases radiation as it breaks down and becomes more stable).

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

regimen (REH-jih-men)

A treatment plan that specifies the dosage, the schedule, and the duration of treatment.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

stem cell (stem sel)

A cell from which other types of cells develop. For example, blood cells develop from blood-forming stem cells.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

surgery (SER-juh-ree)

A procedure to remove or repair a part of the body or to find out whether disease is present. An operation.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

tissue (TIH-shoo)

A group or layer of cells that work together to perform a specific function.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

toxicity (tok-SIH-sih-tee)

The extent to which something is poisonous or harmful.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

transplantation (tranz-plan-TAY-shun)

A surgical procedure in which tissue or an organ is transferred from one area of a person’s body to another area, or from one person (the donor) to another person (the recipient).

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)

will (wil)

A legal document in which a person states what is to be done with his or her property after death, who is to carry out the terms of the will, and who is to care for any minor children.

Source: The National Cancer Institute's Dictionary of Cancer Terms(http://www.cancer.gov/dictionary)